/**
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional information regarding
 * copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License. You may obtain a
 * copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package edu.uci.ics.crawler4j.robotstxt;

import java.util.SortedSet;
import java.util.TreeSet;

public class RuleSet extends TreeSet<String>
{

    private static final long serialVersionUID = 1L;

    @Override
    public boolean add(String str)
    {
        SortedSet<String> sub = headSet(str);
        if (!sub.isEmpty() && str.startsWith(sub.last())) {
            // no need to add; prefix is already present
            return false;
        }
        boolean retVal = super.add(str);
        sub = tailSet(str + "\0");
        while (!sub.isEmpty() && sub.first().startsWith(str)) {
            // remove redundant entries
            sub.remove(sub.first());
        }
        return retVal;
    }

    public boolean containsPrefixOf(String s)
    {
        SortedSet<String> sub = headSet(s);
        // because redundant prefixes have been eliminated,
        // only a test against last item in headSet is necessary
        if (!sub.isEmpty() && s.startsWith(sub.last())) {
            return true; // prefix substring exists
        }
        // might still exist exactly (headSet does not contain boundary)
        return contains(s);
    }

    @Override
    public String toString()
    {
        StringBuilder builder = new StringBuilder();
        builder.append("RuleSet ").append(super.toString());
        return builder.toString();
    }
}
